You wanted to know what states make it a crime to interrupt a 911 call and why states enacted such laws.

SUMMARY

Sixteen states criminalize the interruption of emergency or 911 calls.
These include Indiana, Minnesota, New Hampshire, Ohio, South Carolina, and Texas.
The laws differ in terms of their (1) scope, (2) intent requirements, and (3) penalties.
In most of the states, a violation is a misdemeanor.

Three other states Arizona, Nebraska, and Utah make it a crime to refuse to yield a "party line" or public pay phone in emergency situations (Ariz.
Rev.
Stat.
§ 13-2915, Neb.
Rev.
Stat.
§ 28-1309, and Utah Code Ann.
§ 76-9-202).

Nevada makes it a crime to willfully interfere with any telephone line or obstruct any telephone message, whether or not the call is related to an emergency (Nev.
Rev.
Stat.
§ 707.
910).

We could not determine the legislative intent behind most of the laws in these states because their legislative records are not readily accessible.
But, based on anecdotal accounts from legislative staff in Minnesota, North Carolina, North Dakota, and Texas, it appears that they were enacted because perpetrators of domestic violence were preventing victims from making emergency calls.

EMERGENCY OR 911 CALLS

Scope of the Law

As Attachment 1 shows, 16 states make it a crime to interrupt an emergency telephone or 911 call.
Of these, 13 make interference or interruption a crime, irrespective of the nature of the emergency.
Illinois and Washington's laws apply to domestic abuse perpetrators who interfere with a victim's call for help.
Minnesota has two laws pertaining to interrupting emergency calls.
One law makes it illegal for anyone to interfere with any emergency phone call (Minn.
Stat.
§ 609.
78).
And under the Domestic Abuse Act, it is a crime for batterers to prevent their victims from making a call for help (Minn.
Stat.
§ 518B.
01).

Intention as an Element of the Offense

Twelve states require intentional, knowing, or willful inference with an emergency call or service as an element of the crime.
In New Hampshire, North Dakota, and Oregon, someone is guilty of violating the law if he damages, disconnects, or obstructs access to a telephone with the intent of interfering with an emergency call.
Georgia and Indiana's statutes are even more narrowly drawn.
In these states, someone is guilty if he intends to commit, or aid in the commission of, a crime when interfering with an emergency telephone call.

Intent is not an element of the crime in four states.
In Missouri and South Carolina, someone who merely misuses an emergency service or interferes with a 911 call is guilty of violating the law.
In Illinois and Washington, a culpable mental state does not need to be shown to convict a perpetrator of domestic violence who interferes with a victim's call for help.

Penalties for Violations of the Law

It is a misdemeanor to interrupt an emergency call in most of the 16 states, but penalties vary.
In North Dakota, it is a misdemeanor if the interruption is reckless or knowing, but a felony if it is intentional.
Interference with an emergency call is a felony in Texas if the actor was previously convicted of a misdemeanor under the statute.
In Ohio, it is a felony to interrupt an emergency communication.

Attachment 1:
Comparison of State Laws Criminalizing the Interruption of Emergency Calls